1. Field of the Invention
The invention relates to soil additives, and more particularly, to processes of manufacturing granular secondary and trace mineral soil additives containing e.g. sulfur, zinc, iron and/or other elements. The invention also relates to soil-additive products produced by, or in association with, such processes.
2. Description of Related Art
The iron deficiency known as iron chlorosis affects many crop and landscape plants in the United States and elsewhere. Iron is required to form chlorophyll, for example, which is necessary for photosynthesis and which causes green coloration. An inadequate iron supply in the soil can cause yellow coloration, poor growth and other undesirable effects. Iron chlorosis is especially prevalent in the high-pH soils of the western United States, for example.
Various methods of treating iron chlorosis are known. It is known, for example, to apply elemental sulfur combined with ferrous sulfate to the soil. It is also known to apply iron chelates to the soil during planting or afterwards. For example, U.S. Pat. No. 4,181,516, issued to Gray, Jan. 1, 1980, which is incorporated herein by reference, discloses adding iron chelates to soil to correct iron chlorosis in plants. The iron chelates are prepared by adding ferric iron salts to concentrated solutions of hot caustic effluents from bleach plants of wood pulp mills. In cases of iron chlorosis in trees, it is known to inject ferric ammonium citrate or iron sulfate directly into the trunks. It is also known to apply foliar sprays containing ferrous sulfate, ferrous sulfate heptahydrate, or chelated iron.
U.S. Pat. No. 5,108,481, issued to Shutt, Apr. 28, 1992, which is incorporated herein by reference, discloses a pelletized ferrous sulfate monohydrate product and a method of making the product. Hard, spherical ferrous sulfate monohydrate pellets are manufactured by combining ferrous sulfate monohydrate powder with an aqueous solution of ammonium sulfate in a conventional pelletizing apparatus. The pellets therefrom are heated to remove excess water.
Of course, plants require a variety of nutrients in addition to iron. Zinc, sulfur and other elements are considered necessary for proper growth and development. A wide variety of fertilizer products are known in the art for supplying these necessary elements when deficiencies otherwise exist. However, a need exists for manufacturing heptahydrate metallic salts into a granular form usable to such industries as e.g., fertilizer. There is a specific need for granular heptahydrate trace (micro) element products to treat deficient soils.
For the first time, the inventors of the subject matter disclosed in this application have developed a way to meet the above-described (and other) needs. Embodiments of the invention are used to convert metallic heptahydrate salts, such as iron and zinc sulfates, into agricultural-type (preferably granular) materials such as fertilizer products. More particularly, fertilizer products produced according to embodiments of the invention are highly effective in addressing iron chlorosis and other problems in various plants, including crop plants (e.g. all types of grains, fruit and nut trees, potatoes, onions, vine crops, etc.), and with the added advantage of lower cost.
There is provided an assemblage of granules, the assemblage including a composition and a binder. The composition may include at least one crystalline hydrated metal salt. The binder may be present in an amount sufficient to bind the crystalline hydrated salt into granules. The composition may include ferrous sulfate heptahydrate and zinc sulfate heptahydrate. The composition may include between about 10% and about 15% iron by weight and between about 3% and 7% zinc by weight. The binder may include humate, which may be present in an amount between about 20% and 40% by weight.
There is also provided a process for making an assemblage of granules, the process including mixing a composition and a binder and granulating the binder- composition mixture with a quantity of water. The composition may include hydrated ferrous sulfate and hydrated zinc sulfate. The binder may include a humate. The process may further include drying the granulated composition and binder. The drying may continue until a slight melt is formed in the granules. The process may further include cooling the dried granules.
There is further provided an assemblage of granules made by a process including mixing a composition and a binder and granulating the binder-composition mixture. The composition may include ferrous sulfate heptahydrate and zinc sulfate heptahydrate. A quantity of water may be added during granulation. The binder may include humate. The granules may be exposed to a first temperature until a slight melt is present in the granules. The granules may be further exposed to a second temperature, the second temperature less than the first temperature.
There is still further provided a process of applying an assemblage of granules to plants to prevent or alleviate chlorosis. The process may include providing the assemblage of granules and applying the assemblage to the plants such that the ferrous sulfate and zinc sulfate are available to the plants. The assemblage of granules may include ferrous sulfate heptahydrate and zinc sulfate heptahydrate combined with a binder, the binder including humate. The assemblage of granules may be applied directly to the soil. Or the assemblage of granules may be dissolved or suspended in an aqueous solution and the aqueous solution applied to the soil or as a foliar application.
Embodiments of the invention include processes to manufacture granular secondary and trace mineral soil additives containing significant amounts of iron, zinc and/or sulfur. A mixture of finely ground humates and ferrous/zinc sulfate is produced, according to one embodiment, and is granulated in e.g. a drum or pan granulator. The resulting material is dried, screened and then bagged for use in a fertilizer product for ultimate mixing with other fertilizer-type materials and application to e.g., high-pH soils commonly associated with chlorotic plant conditions. To the inventors"" knowledge, this is the first time it has been recognized that ferrous sulfate heptahydrate and zinc sulfate heptahydrate can be used in the production of a granulated-type fertilizer product.
The chemical composition and analysis of actual starting materials may be quite variable. Starting materials include commercially available ferrous sulfate heptahydrate, zinc sulfate heptahydrate, and other hydrated salts derived from reacting metals with sulfuric acid, e.g., galvanization byproducts.